, the latest in a series of outages to affect rival companies in the industry.
"Earlier tonight we experienced an issue with our weight reporting system, which caused system wide flight delays," the airline said in a statement on its Twitter feed.
"We have resolved the issue and are working to get customers to their destinations as soon as possible. We apologise for the inconvenience."
Passengers said they had been forced to wait onboard planes or inside terminals as flights were delayed for several hours.
"On the plane for more than an hour, away from the gate and no communication. What's happening?," one passenger tweeted.
In Paris, passengers complained as check-in lines grew for a flight to New York, a Reuters reporter said on Friday morning.
The airline said the problem had been resolved as of 1700 AEST on Friday.
It is the third computer glitch to hit United's owner United Continental Holdings in recent months and the latest in a series of problems that have tested the reliance on technology of some of the world's largest carriers.
